Shelf



FIG. 1 is a front right side perspective view of a shelf showing our new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a back elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines in the drawings are for illustrative purposes only and form no part of the claimed design. 

We claim the ornamental design for a shelf, as shown and described. 